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The 45RFE and its close relative the 545RFE (and the later 68RFE big brother) live under a lot of Chrysler iron: Grand Cherokee WJ/WK, Dodge Durango, Dakota, Ram 1500, and more. They are tough, but they get treated like they are maintenance-free, and they are not. The single most important thing to know before you touch one is this: it has two filters, and the parts-store "kit" you grabbed may only include one of them.
Miss the second filter and you have done half a service while telling yourself you did a full one. Below is what a real fluid-and-filter change costs, what it involves, and the level-check procedure on the no-dipstick trucks that trips people up.
The Dual-Filter Design — Do Not Skip the Second One
The 45RFE/545RFE uses two filters inside the pan:
- The primary (spin-on style) filter — the main pickup filter, the one everybody replaces.
- The cooler-return filter — a smaller secondary filter that catches debris coming back from the cooler. It presses/bolts into the valve body area and is the one that gets left in the pan.
A proper "trans filter kit" for these should include both filters plus the pan gasket. If your kit only has one round filter and a gasket, it is incomplete. The cooler-return filter is cheap and it is right there once the pan is off — there is no excuse to leave a used one in a truck you are servicing for the next 30,000-plus miles.
Check 45RFE/545RFE filter kits
Fluid — ATF+4, Nothing Else
The 45RFE and 545RFE call for ATF+4 (Chrysler MS-9602) and only ATF+4. Do not put Dexron/Mercon or a generic multi-vehicle ATF in one of these to save a few dollars. ATF+4 is a specific low-friction synthetic-blend fluid, and these transmissions shift on precise clutch friction; a substitute fluid causes shudder, harsh engagement, and premature clutch wear. "Compatible with ATF+4" on a jug is not the same as licensed ATF+4 — look for the actual Chrysler MS-9602 spec.
Check ATF+4 fluid
Capacity — Drain-and-Fill vs Full Fill
There are two very different numbers here and mixing them up is how people either underfill or waste fluid.
| Service Type | Approx. Fluid Needed | What It Does |
|---|---|---|
| Pan drop / drain-and-fill | ~5 quarts | Replaces what is in the pan. Torque converter still holds old fluid. |
| Drain-and-fill + both filters | ~5-6 quarts | Same as above plus fresh filters. The standard DIY service. |
| Full fill (dry / rebuild) | ~13-14 quarts | Total system capacity with a dry converter. Not a routine service number. |
| Flush / exchange | ~12-14 quarts | Machine exchange to replace nearly all fluid including converter. |
A normal maintenance service is a pan drop: you get back roughly 5 quarts, replace both filters and the gasket, and refill with the same amount you drained. Because a plain drain does not empty the converter, a lot of people do two drain-and-fills a few hundred miles apart to refresh more of the total volume without paying for a machine flush.
Cost — DIY vs Shop
| Approach | Cost | What's Included |
|---|---|---|
| DIY drain-and-fill + both filters | $60 - $120 | ~6 qt ATF+4, dual-filter kit, gasket. Your labor. |
| Shop drain-and-fill + filters | $150 - $300 | Parts, fluid, labor at shop rate. |
| Shop machine flush/exchange | $250 - $400 | Full-volume exchange, usually no filter unless requested. |
The DIY math is compelling: the fluid and a proper dual-filter kit run you well under half of what a shop charges, and the job is a driveway job if you can get the truck up safely and manage a pan full of ATF+4 without wearing it. The only real skill points are dropping the pan cleanly and getting the fill level right afterward — which is the next section.
The No-Dipstick Fill Check (Later Models)
Early 45RFE trucks have a dipstick and you check level the normal way: warm, in park or neutral, on level ground. Many later 545RFE applications deleted the dipstick, and the fill procedure is temperature-based, not eyeball-based:
- Vehicle level, engine running, transmission at a specified temperature window (commonly around 110-120°F / check the exact spec for your model — you read temp with a scan tool).
- With the engine running and the trans at that temperature, you open the fill/check plug and add fluid until it just trickles out, then close it. Fluid that runs out means it is at level for that temperature.
- Check too cold and you will overfill; check too hot and you will underfill. Temperature is the whole game on these.
This is why a scan tool that reads transmission fluid temperature is genuinely useful on the dipstick-less trucks — you are setting level by temperature, not by a stick.
Check scan tools that read trans temp
Symptoms of Overdue Fluid
- Harsh or clunky 1-2 shift when cold that smooths out as it warms — classic tired-fluid behavior.
- Torque converter shudder at light throttle around 40-50 mph as the TCC applies. Degraded fluid loses the friction properties the converter clutch needs.
- Delayed engagement into drive or reverse after sitting.
- Flare or slip on the 4-5 upshift on the 545RFE.
- Dark, burnt-smelling fluid. Healthy ATF+4 is red and clear; brown and burnt means overdue, and if it is truly cooked, a fluid change alone may not save it.
Interval: Chrysler's severe-service guidance for these lands around every 30,000 miles for a fluid and filter change if you tow, plow, idle a lot, or run dusty/hot conditions. Normal-duty intervals are longer, but on a truck of unknown history, treat it as severe and get fresh fluid and both filters in it now.
Need the Dual-Filter Kit or ATF+4? Ships Same-Day
Our companion shop gearboxinsider.com stocks complete 45RFE / 545RFE dual-filter kits with the cooler-return filter included, pan gaskets, and licensed ATF+4. Same-day ship before 2pm Eastern.
Shop Gearbox Insider →FAQ
Do I really need to replace both filters, or is the primary enough?
Replace both. The cooler-return filter is a separate element from the main pickup filter, it catches different debris, and it is already exposed the moment the pan is off. Leaving the old one in defeats half the point of the service and it is a few dollars. Buy a kit that clearly lists two filters.
Can I use a universal ATF instead of ATF+4?
No. The 45RFE/545RFE needs licensed ATF+4 (MS-9602). Universal or "compatible" fluids frequently cause converter shudder and harsh shifts in these transmissions. The fluid is not expensive enough to gamble a transmission on.
My later model has no dipstick — how do I know it is full?
You set the level by fluid temperature. With the truck level and engine running, bring the transmission to the specified temperature window (read with a scan tool), open the check/fill plug, and add until fluid just weeps out, then close it. Checking cold overfills it; checking hot underfills it.